CVE-2026-67869Public exploitNetwork attack vector

Server crash via forged Acknowledge method metadata

Published Aug 5, 2026 · Updated Aug 5, 2026

Type confusion in open62541 1.5.5 allows remote attackers to crash an OPC UA server through a crafted Acknowledge method call. Service_Call validates arguments against mutable InputArguments metadata, but acknowledgeMethodCallback casts the first value to UA_ByteString without rechecking its type. Exploitation requires a session permitted to modify method metadata; a forged Boolean is read as a ByteString, causing an out-of-bounds read and server crash.

CVSS severity7.5
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in open62541 1.5.5 allows remote attackers to crash an OPC UA server through a crafted Acknowledge method call. Service_Call validates arguments against mutable InputArguments metadata, but acknowledgeMethodCallback casts the first value to UA_ByteString without rechecking its type. Exploitation requires a session permitted to modify method metadata; a forged Boolean is read as a ByteString, causing an out-of-bounds read and server crash.

The record

CVE
CVE-2026-67869
Published
Aug 5, 2026
Updated
Aug 5, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5MITRECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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